Refining wool fat



Aug. 18, 1953 H. J. PASSINO ETAL 2,649,466

REFINING WOOL FAT Filed Oct. 25, 1947 2 Sheets-Sheet l L\J g a S 0 INVENTORS m J 2 HERBERT J.PASS|NO 5 JAMES M.MEYERS g 5Y6:

. ATTORNEYS Aug. 18, 1953 Filed Oct. 25, 1947 FIG. 2

H. J. PASSINO ET AL REFINING WOOL FAT 2 Sheets-Sheet 2 Q ne I36 l 38 L7 I N N N 3 m N U =1 \0 (2 1 m (n 3 P U z 0 INVENTORS i 1 HERBERT J.PASSINO O JAMES M. MEYERS 3 2 BYc. a xzzuut ATTORNEYS Patented Aug. 18, 1953 UNITED STATES 'A'i'ii'l' OFFICE REFINING WOOL FAT corporation of Delaware Application October 25, 1947, Serial No. 782,174

12 Claims. (01. 260-426) This invention relates to an improved process for refining wool fat and to a new method for treating wool fat to separate it into valuable fractions.

As used in this specification and claims the term wool fat relates principally to wool grease, which is the raw material obtained by treating raw wool with a scouring solution or solvent. Wool grease is obtained principally by scouring the raw wool with dilute soap or alkaline solutions. Varying amounts of alkali may be added to the soap solutions if required by the type of wool being treated. The wash liquid is then withdrawn from the wool and treated to remove the soap solution from the wool grease. This may be accomplished by centrifuging, which yields a relatively dry product, or by acidification and settling, which yields a wet, relatively poor quality material, degras. Wool grease may be separated from raw wool also by means of suitable solvents, such as petroleum ether.

The term wool fat as used in the following specification and claims also includes wool wax, which is neutralized wool grease, and lanolin, which is hydrated wool fat.

In accordance with the improved method of this invention the wool fat is neutralized, if not already neutral, and treated under carefully controlled conditions with a suitable solvent to separate a small fraction of the wool fat which are concentrated the color bodies of the original wool fat. The remainder of the wool fat, comprising all but a minor percentage of the original wool fat, is recovered as a refined neutral product of very light color and is suitable for any of the uses to which refined wool waxes ordinarily are adapted. In a preferred modification the invention also comprises separation of the refined wool fat into a solid wool fat wax and a liquid wool fat oil. The improved process also includes in a preferred modification the step of concentrating the sterols of the wool fat into a fraction which is recovered as a separate refined product of the process.

The treatment of the wool fat to remove color bodies and to concentrate the sterol content of the wool fat involves, in accordance with the iinproved process, treatment of the wool fat by means of a selective solvent at temperatures in a range extending from about 100 F. below the critical temperature of the solvent to a few degrees above the critical temperature of the solvent. Since the fractionation requires the use of solvents which are not miscible in all proper tions at the operating temperature, the solvents employed in the process are those whose critical temperatures are not substantially higher than 450 F. Preferably, the process employs solvents whose critical temperatures are lower than 325 F., in order to avoid high temperatures, which might injure the wool fat.

The low-boiling hydrocarbons represent a desirable class of solvents because of their relative inertness and low cost. The low-boiling olefins may be employed, but they are less desirable than the low-boiling paraffins, as the parafiins are more inert. Of the paraffins, propane and the butanes are preferred ordinarily because of the high degree of solubility of the wool fat in these solvents and their relatively low critical temperatures, which permit operating the process in a temperature range not injurious to the wool fat. However, ethane or the pentanes can be employed as solvents in the process. While relatively pure hydrocarbons ordinarily are preferred, mixtures of solvents may be employed. For example, mixtures of ethane and propane, or mixtures of propane and butane, or mixtures of methane and butane may be employed in suitable proportions.

While the low-boiling hydrocarbons are advantageous for use in the process because of their low cost other solvents having relatively low critical temperatures may be employed, such as ammonia, dichlordifluoromethane, dimethyl ether, methyl fluoride, and halogenated hydrocarbons in general.

It will be understood that, since the solvents employed are either normally gaseous or would be vaporized at atmospheric pressure at the temperatures normally employed in the process, it is necessary to impose on the treating zone a substantial super-atmospheric pressure to maintain the contents of the zone in liquid condition, and when relatively high temperatures are employed this may involve an operating pressure of 500 to 1000 pounds per square inch.

The invention will be described further in more detail by reference to the accompanying drawings, in which Fig. 1 is a diagrammatic view in V such apparatus and lines in 1 applies also to the same pieces of equipment and lines shown in Fig. 2.

The invention will be described in detail by reference to the treatment of wool grease as defined above, although it will be understoodthat the methods of operation are applicable also to the treatment of wool wax. and lanolin,. as defined above. In the further description of the invention propane and butane will be referred to as the solvents, but it is to be understood that tom of tank 23 through line 25.

this material may be introduced through line 25 the principles of operation are the same in the use of any of the preferred solvents mentioned above, the operating conditions being changed only in accordance with the composition of the wool fat and the physical properties of the solvent.

In Fig. 1 the principal piece of equipment employed is an elongated vertical fractionatin column or solvent extraction tower l0. Tower i9 is adapted to produce intimate contact of counter-flowing liquid phases and thus may be equipped with suitable contact means, such as packing, bafiles, or trays. The solvent for use in tower I0 is supplied from reservoir tank II. The supply of solvent in tank I l is maintained by the return of solvent recovered in the process and by the addition of small amounts of makeup solvent from line I2 containing a, pump i3. The solvent circulated in the process in a circuit including tank I i is maintained at somewhat higher temperatures than another quantity of the same type of solvent used in another part of the process. Consequently, the solvent circulating through tank i I will be referred to as hot solvent to distinguish it from the other cold solvent whose use will be described below.

Hot solvent from tank H is transferred to a low point in tower ill through line I4 by means of pump 15. Heating means It are provided in line M to heat the solvent to the temperature desired in the bottom of tower I0. The solvent flows upwardly in tower H] as a substantially continuous phase in counter-current contact with a descending lower phase liquid stream containing wool fat, and the final extract solution is withdrawn from the top of tower l0.

The wool grease to be treated in the process is introduced through line ll by means of pump I8. To render the wool grease charge easier to pump, it may be diluted with a small portion of the solvent prior to introduction of the charge through line H. While the wool grease may be treated in tower Ii! without prior neutralization, it is preferred in accordance with this invention to neutralize the wool grease before treatment in tower l0 rather than neutralize the products obtained from tower 10. In accordance with this preferred modification a suitable alkali, such as an aqueous solution of sodium hydroxide, having a concentration of 10 to 50 percent, is introduced into line H from line H) by means of pump 26. A mixer 2| is provided in line H to produce intimate mixing of the wool grease and alkali solution and complete the neutralization reaction.

The mixture of neutralized wool grease, alkali solution and soaps may be introduced directly into tower ID at an intermediate point to effect in tower I0 simultaneous fractionation of the neutral wool grease and separation and washing of wool grease from the soaps and alkali solution. Alternatively, a preliminary separation of the soaps and neutral oil is effected outside tower I0. For this purpose the mixture is passed from line I! through line 22 to a settling tank 23. From settling tank 23 the neutral wool fat is transferred to tower W at an intermediate point thereof by means of line 24. The mixture of soaps and alkali solution is withdrawn from the bot- Alternatively,

into tower ID at a point near the bottom thereof to effect washing of the soaps by the fresh solvent to recover entrained wool fat.

' Aside from the washing of soaps which may be, introduced into the lower portion of tower ID, the function of this tower essentially is solvent fractionation of the wool grease with the liquefied solvent in counter-current contact under refluxing conditions. Tower I0 is operated to separate a final solvent phase overhead, which contains the greater part of the wool grease in solution, and to separate a final raffinate phase as a bottoms product containing a concentration of the color bodies of the wool grease charged to tower l0. Tower II) is constructed in a manner to stand a sufficiently high internal pressure to maintain the solvent in a liquefied condition under the highest temperature to be used in the tower. This maximum will depend upon the boiling characteristics and the critical temperature of the solvent or solvent mixture employed.

For efficient operation of tower [0 it may be desirable or necessary to heat the contents or the tower to maintain differentials in pressure between certain locations in the tower. This may involve heating the upflowing solvent phase in the upper part of the tower to maintain a tempera ture differential or gradient between the top of the tower and the lower part of the tower. Heating means for this purpose are indicated diagrammatically by coils 21, which are placed above the point of introduction of the wool grease. It will be understood, however, that the location of the heating coils depends entirely upon the location at which it is desired to supply heat.

In the normal operation of tower Hi the solvent stream introduced through line M fiows upwardly in tower I0 in counter-current contact with a relatively heavy lower, or rafiinate, phase. The volumetric ratio of solvent to wool grease, and the temperature, pressure, and reflux conditions are regulated whereby the wool grease and solvent are only partly miscible, whereby there are formed a solvent or extract phase and a lower or raifinate phase. The solvent phase contains all but a small proportion of the solvent employed and that proportion of the wool grease which it is desired to extract. The lower phase, or raffinate phase, contains only a small proportion of the solvent and a larger proportion of the wool grease in a solvent: fat ratio much lower than the corresponding ratio in the extract phase. The rafifinate, or lower, phase is susbtantially heavier than the extract phase and flows downwardly in the tower to the bottom thereof.

Facilities are provided for maintaining the pressure on tower l0 suificiently high to maintain the contents thereof in liquid condition and provide a suflicient margin over the minimum pressure necessary at the highest temperature to permit slight adjustments of pressure during the operation. The maximum temperature employed in tower l0 ordinarily will not be more than or F. above the critical temperature of the solvent, and ordinarily the maximum temperature in tower II! will be lower than such critical temperature. The critical temperature of propane is 206.3 F. and the critical pressure is 617.4 p. s. i. The critical temperature of normal butane is 307.6 F. and the critical pressure is 529.2 p. s. i. Thus, when using propane as the solvent the maximum operating pressure will be in the range of 600-700 p. s. i. while the maximum pressure necessary when employing butane will be somewhat lower.

The temperature in the top of tower H) is maintained at the level necessary, in view of the solventzfat ratio employed, the degree of refluxing employed, and the pressure on tower Hi, to dissolve in the solvent phase at that point only those ingredients of the wool fat desired in the overhead roduct of tower [0. In general, it may be said that relatively high temperatures in the top of tower H) are associated with relatively high solvent:fat ratios and relatively low reflux ratios. When employing propane as the solvent the temperatures necessary in the top of tower l0 ordinarily are in the range of l220 F. When employing normal butane the top tem peratures in tower l0 ordinarily will fall within the range of 270-320" F. If a mixture of normal and iso-butanes is employed the top temperature in tower l0 may be as low as 250 F.

The temperature in the bottom of tower H], which is controlled by the temperature of the incoming stream of solvent, may be maintained at the same level as the top temperature. Preferably, however, for efficient operation a substantial temperature gradient is maintained in tower Ill. The range of temperatures employed in the bottom of tower l0 when using propane is approximately 140-220" F. When employing the butanes the bottom temperature ordinarily will not be lower than about 200 F. The temperature differential between the top and the bottom of tower l0 may vary from 1 F. to 60 F. In general, the range of operating temperatures is from a temperature 15 to 20 F. above the critical temperature of the solvent to a temperature F. below such critical temperature.

The top and bottom temperatures contained in tower I0 must be correlated to permit withdrawal of wool fat from the top and bottom of tower 10 in the desired ratio and at a combined rate of withdrawal equal to the rate at which wool fat is charged to tower 10 from line I! plus the rate of return of wool fat to tower H) as reflux material. The bottom temperature is selected with the object of excluding from the lower phase withdrawn from the bottom of the tower as much as possible of the constituents of the fat which it is desired to include in the overhead product. However, the temperature in the bottom of tower I0 must be maintained above any temperature at which there occurs complete miscibility of the fat with the solvent in all proportions. A relatively low bottom temperature is maintained in tower it! when it is desired to withdraw as a bottoms product only a small proportion of the fat charged to tower Ill, as when operating tower Hi to decolorize the wool fat. In general, relatively high bottom temperatures are associated with relatively high solventzfat ratios, and vice versa.

The efficiency of tower I0 in concentrating the color bodies in a small railinate phase is due to the intensive refluxing of the tower which is carried out at one or more points above the points of introduction of fat into tower 10. Such refluxing may be achieved by maintaining a substantially higher temperature in the top of the tower than at lower points in the tower. The solvent phase which has become saturated with fat in the lower part of tower I0, at the temperature prevailing there, is heated in the top of the tower to a temperature at which it is unable to retain all of the fat dissolved therein. This results in precipitation of a part of the fat previously dissolved in the solvent phase. The precipitated fat forms a separate, relatively heavy, liquid phase containing a small amount of solvent in a solvent:fat ratio much lower than that of the solvent phase.

The solvent phase may be heated from the lowest temperature in the tower to the highest temperature at any one of the points occupied by heating coils 21. It is preferred, however, to heat the solvent phase to successively higher temperatures as it passes upwardly in contact with the series of heating coils 21, in order to induce precipitation along the length of the zone occupied by coils 21. While these coils may be located entirely above the charging point of' the wool fat, as indicated in Fig. 1, the operation is not limited to this arrangement, as heating elements may be provided below the charging point or along the entire length of tower l0.

Tower ID is divided into two zones by the wool iat charging point. The upper zone is the rectification zone, whose function is the separation of the constituents of the wool fat. The lower zone is primarily a stripping zone, in which the undissolved wool fat and the lower phase material precipitated in the rectification zone are subjected to the stripping action of the solvent stream to dissolve in the solvent stream all constituents of the fat which it is desired to exclude from the final rafiinate phase. Rectification also occurs in the stripping zone as an inherent part of the counter-current stripping treatment and as a result of the passage into the stripping zone of the relatively more soluble lower phase material precipitated in the rectification zone. That part of the latter material which is not redissolved in the lower parts of the rectification zone combines with the undissolved portion of the charge to form a combined lower phase which flows downwardly through the stripping zone. As the solvent flows up from the bottom of tower l0 it absorbs fat until it is saturated. Thereafter, any additional quantities of fat dissolved by the solvent stream in the stripping zone are balanced by corresponding precipitation of less soluble portions of the fat.

The rectification of the solvent phase in the stripping zone is intensified if a temperature gradient is maintained in that zone. Whether or not the temperature gradient in tower I0 is maintained throughout the length of the tower depends somewhat upon the extent of stripping which is made possible by the facilities provided. If the principal function of tower I0 is the recovery of ingredients from the bottom phase, as when employing the tower for decolorizing, it may be desirable to maintain the stripping zone substantially uniformly at the lowest temperature, whereby the temperature of the solvent phase at the fat chargepoint'issubstantially the same as the bottom temperature. Alternatively, a slight temperature gradient may be maintained in the stripping zone, in combination with a greater temperature gradient in the rectification zone.

In the rectification zone the solvent phase is subjected to treatment which continuously reduces the solvent power of the solvent phase for the less soluble constituents of the fat, as the solvent phase flows upwardly through the rectification zone. This results in the precipitation of the lower phase, as described, and the linear velocity of the solvent phase must be maintained sufiiciently low in the rectification zone to permit the downward flow of this lower phase. As the lower phase flows downwardly from a point of precipitation it contacts solvent phase which is at a lower temperature and which contains fat dissolved therein in excess of the equilibrium amount at that temperature and also contains an excessive quantity of the less soluble constituents of the fat in View of the composition of the lower phase with which it is in contact at that point. As a result of all these effects there is absorption of a art of the downfiowing lower phase and precipitation from the solvent phase of the previously dissolved fat. Consequently, as the lower phase flows downwardly in the rectification zone it is subjected to the stripping action of the solvent phase whereby the more soluble portions of the fat are redissolved and whereby less soluble portions are precipitated to the lower phase. This effect occurs throughout the length of the rectification zone, whereby the fat in that zone is subjected to continuous pre' cipitation, resolution and reprecipitation.

Instead of heating means 21, other means may be provided to regulate the temperature of the solvent phase. For example, a portion of the solvent may be diverted from line 14, heated to a temperature above the bottom temperature, and introduced into tower ID at an elevated point. The fat charge to the tower through line H also may be preheated to assist heating the solvent phase. Furthermore, a portion of the solvent may be premixed with the fat charge before admission of the latter to tower N]. This is particularly desirable when the fat is a solid or a highly viscous liquid at the temperature at which it is to be charged,

In addition to the maintenance of a temperature gradient in the rectification zone to decrease the solvent power of the solvent phase for the less soluble constituents of the fat, this effect can be achieved by changing the pressure or by preferentially dissolving in the solvent phase portions of the fat which are more soluble therein than some of the fat previously dissolved in the solvent phase. The methods involving control of temperature and pressure may be employed independently, but each also involves the preferential resolution in the solvent phase of portions of the fat which are more soluble therein than some of the fat previously dissolved when the lower phase, formed by precipitation, is flowed through the rectification zone in counter-current contact with the solvent phase. However, the establishment of a lower phase and the rectification of the solvent phase can be effected without varying the temperature or pressure. Rectification of tower in by varying the pressure is a less desirable method, as it requires dividing the rectification zone into a series of separate compartments. The solvent phase would then be passed through such separate compartments at progressively lowerpressure to effect precipitation in each compartment. would then be pumped into the next lower compartment. This method of operation requires more elaborate equipment and is less eflicient.

Alternative to the maintenance of a tempera,

ture gradient, or in combination with that method, the solvent power of the solvent phase.

of the fat component of the final solvent phasewithdrawn from the top of tower if! and re-. turning it to the top of the tower. In accordance with this method of operation the solvent phase passes out of tower 50 through line 28 to an overhead receiver 29. The pressure is reduced at valve 313 to permit all, or substantially all, of the solvent to evaporate. This operation may be assisted by heating the mixture, as by heating means (H in line 28. Instead, receiver 29 may be maintained at the tower pressure while evaporating the solvent solely by the application of heat. In either operation it is not essential to evaporate the solvent entirely, and it is ordinarily preferable to efiect only partial evaporation whereby some solvent is left in the liquid phase in receiver 29. In the arrangement illustrated in Fig. 1, all the solvent phase from tower H) is shown as flowing through line 28 to receiver 29. It is evident, however, that the reflux liquid required may be obtained by passing to receiver 29 only a part of the solvent phase from tower l0, containing fatty constituents in the amount required for refluxing. In that case the remainder of the solvent phase is passed elsewhere for further handling.

The solvent evaporated and separated in receiver 29 is withdrawn therefrom through line 32, which connects with hot solvent storage tank I l. A cooler 33 is provided to recondense the vaporized solvent.

The liquid phase material remaining in receiver 29 is withdrawn through line 34. That part of this material desired for refluxing tower I0 is diverted from line 3A through line 35 which is provided with a pump 36 and connects with the upper part of tower I0. If desired, temperature control means may be provided in line 35 to bring the reflux liquid to the desired temperature.

The reflux liquid which is returned to tower 10 through line 35 is more concentrated in fats than is the solvent phase at the reflux point in tower 10. Since the solvent phase at that point is substantially saturated with fats the introduction of reflux liquid causes a redistribution of the fat at that point. The more soluble portions of the reflux liquid are dissolved in the solvent phase and there is a corresponding precipitation of less soluble fatty constituents from the solution. The precipitate and the undissolved portion of the reflux liquid form a second liquid phase which then flows down tower ID in countercurrent contact with the upwardly flowing solvent phase. As the lower phase flows downwardly there is a continuous redistribution of fat between the solvent phase and the lower phase. At each point in the rectification zone the most soluble fatty constituents of the lower phase are dissolved in the solvent phase, with a correspond- The precipitate in each compartment.

ing precipitation of less soluble fatty constituents in the solvent phase. Thus the lower phase becomes more concentrated in the less soluble portions of the fat as it passes down the tower and the solvent phase becomes more concentrated in the more soluble constituents of the fat as it passes upwardly through the rectification zone.

The operating factors described above in connection with the use of a temperature gradient for refluxing tower Hi generally are applicable to the method of operation involving external refluxing, except that a somewhat lower top temperature is required in the tower to carry overhead in the solvent phase the somewhat larger quantity of fat which is required to provide reflux liquid. When operating tower it with external refluxing through line 35 the temperature may be uniform from top to bottom of the tower. This temperature may be one which would cause complete miscibility of the fat with the solvent in the ratio in which these are charged to the tower but which under equilibrium conditions produces only partial miscibility. Tower Hi may be brought to equilibrium conditions by returning all the overhead product through line 35 until the quality of that product is satisfactory. During that time the accumulation of reflux fat in the solvent phase in the tower lowers the solvent power of the solvent phase for the fat charge to the point at which the solvent phase has the desired selectivity as a solvent. In any of the above methods of operating tower if! the ratio of solvent to fat charge to tower It should be relatively high. A ratio of at least 3:1 is generally necessary, and ratios as high. as 100:1 may be employed. The temperature gradient and external refluxing methods of accomplishing. rectification of tower ill advantageously are combined in a single operation. Thus, while the temperature gradient is maintained by means of heating coils 2i, tower ill is refluxed through line 35. This combined method of operation provides close control of the operation of the tower.

The raifinate phase collects in the bottom of tower l and the upper level of this phase may be maintained at any desirable height which may be above or below the point at which the solvent is introduced from line I4. Lower phase material is withdrawn continuously from the bottom of the tower through line 3].

To illustrate the operation of tower H] in the decolorizing of crude wool grease reference is made to the following examples.

EXAMPLE I In this operation the fractionation of wool grease to effect decolorization was carried out in a continuous fractionating zone provided by two- 18'foot towers, the first being a 4-inch bafiled column and the second a 2-inch packed tower. The propane solvent was introduced at a point 2 feet from the bottom of the first tower, and the extract phase from that tower was introduced at a point 2 feet from the bottom of the second tower. The wool grease was introduced at a point 4 feet from the top of the first tower, and the lower phase from the bottom of the: second tower was pumped back to the top of the first tower at a point 1 foot from the top thereof. The color bodies concentrate was obtained as a lower phase in the first tower and the decolorized wool grease was obtained in solution in the extract phase withdrawn from the top of the second tower. This operation, carried out for purposes of convenience in two towers, provided therefore in effect a single continuous fractionating zone which would be provided by a single tower of the necessary length. The two towers employed in this example provided a length of 12 feet in the stripping zone and a length of 20 feet in the rectifying zone. The temperature at the top of the second tower was maintained at 174 F., While the temperature at the bottom of the first tower was 110 F. The temperature at the wool grease charging point was 113 F. Thus the temperature gradient in the rectifying section was 3 F. per foot, while that in the stripping section was 0.25 F. per foot.

The wool grease was charged to the process at the rate of 256 pounds per hour per square foot of cross sectional area of the 2-inch tower, while propane was charged at the rate of 4610 pounds per hour per square foot. The propane velocity was 145.7 feet per hour on the basis of the 2inch tower. The residence time was 34.6 minutes. The propane:wool grease ratio was 33.5 by volume and 17.9 by weight. The reflux ratio, which is the ratio of overhead product of the second tower returned as reflux to the ratio of such product withdrawn from the system, was 0.85. The wool grease feed was premixed with 2.1 volumes of propane to increase fluidity. The results obtained in this operation are indicated in the following table, in which are set forth the analyses of the crude wool grease and the products recovered from the bottom of the first tower and the top of the second tower.

Table 1 Crude i Over- Bot- Analysls gggsle head toms.

Oil Yields, Wt. Percent 69. 6 30.4 Free Fatty Acids, Percent (as Oleic). 8. 23 5. 54' 13. 4 Free Fatty Acid Recovery, Percent. N 46. 8 49. 4 Unsaponifiable Oil, Wt. Percent 42. 3 47. 1 28. 6 Unsaponifiable Oil Recovery. Percent--. 77. 5 20.6 Iodine No. (W1'js) 41. 7 41. 2 38.2 Saponification No 117 134 Color, Gardner- 18 9 18 Color, N PA. 1 4 2+ 2 3 6 Moisturc'and Volatlllty, Wt. Percent 1. 23 0. 07 0. l7 Sulfur, Wt. Percent 0. 52 0. 43 0.83 Sulfur Recovery, Percent 57,. 6 4 8, 5 Melting Point, 0.. 39.0 37.0 48.0 Ash, Wt. Percent 0. 08 0. 00 0; 1 7 Specific Gravity 0. 948 01 927 1.- 009 1 Single dilution. 2 Double dilution.

In this operation the crude wool grease, obtained from the wool by solvent extraction with naphtha, was. separated into a 69.6 overhead fraction of greatly improved color, and the physical and chemical properties of the overhead product otherwise were substantially different from the properties of the crude wool grease. The presence of sulfur in the product results from chemical treatment of the sheep. When insecticid'es free from sulfur are employed sulfur is not an important factor in the wool grease products. Sulfur may be removed before or after processing by treatment with sodium sulfite. Conveniently this treatment can be carried out by adding sodium suli-lte to a- 1-0 percent caustic solution employed for neutralizing the wool grease.

A blend of overhead productsobtained in the operating run exemplified by Table 1- was further fractionated in two different operations to produce asmall final overhead fraction: and a somewhat larger final overhead fraction. The conditions employedlin: these operations, designated below as Operation A and Operation B,. were as follows:

1 1 Table 2 Operating Conditions Tem lperatine, F.:

Height of Stripping Section, Ft

The results obtained in Operations A and B are indicated in Tables 3 and 4 below, in which are set forth analyses of the charge stock and the overhead and bottoms products in Operations A and B.

Table 3 Analysis Charge Over- Bothead toms Oil Yields, Wt. Percent 10. 2 89. 8 Free Fatty Acids, Percent (As Olei 1o. 6 3. 35 'Free Fatty Acid Recovery, Percent. 34. 4 65.0 Unsaponifiable Oil, Wt., Percent 47. 7 60. 9 47.0 Unsaponifiable Oil Recovery, Percent 13. 88. 5 Iodine No. (Wijs) 44. 6 21. 7 47. 6 Saponification No 101 113 97 Color, Gardner. ll- 9 12- Color, NPA 4T- 2 4- Moisture and Volatility, Wt. Percent. 0. 66 0.54 0.09 Sulfur, Wt. Percent 0. 44 1. 79 0. l0 Sulfur Recovery, Percent 41. 5 20. 4 Melting Point, C 55. 2 40. 4 Ash, Wt. Percent 0. 00 0. 00 Specific Gravity 0.926 0.893 0.930

Table 4 Analysis Charge Over- Bothead toms Oil Yields, Wt. Percent 27.0 73.0 Free Fatty Acids, Percent (As Oleic)... 4. 63 11. 6 2. 27 Free Fatty Acid Recovery, Percent 67. 6 35.8 Unsaponifiable Oil. Wt. Percent 47. 7 57. 4 44. 2 Unsaponifiable Oil Recovery, Percent. 32. 5 67.6 Iodine No. (Wijs) 44. 6 41. 0 47. 8 Saponification No 101 117 98 Color, Gardner..- 11- 9 12 Color, NPA 4- 2 4 Moisture and Volatility. Wt. Percent- 0. 66 0. 05 0. 09 Sulfur, Wt. Percent 0.44 l. 27 0. l2 Sulfur Recovery. Percent. 77. 9 19. 9 Melting Point, C 36. 2 44. 8 40. 4 Ash, Wt. Percent 0. 0 0. 00 0.00 Specific Gravity O. 926 0.913 0.931

In Operation A the percent final overhead fraction represented a concentration of unsaponifiable components. After removal of sulfur and fatty acids this product would contain 80 percent unsaponifiable components and thus constitute a highly concentrated sterol product of the process, of light color and low iodine number. The overhead product of Operation B also was a highly concentrated sterol product representing a somewhat higher recovery of unsaponifiables.

The overhead product of the first operation, identified in Table 1, was subjected to fractional crystallization by chilling in pentane. In this operation the decolorized wool grease was dissolved in 5 volumes of pentane. The solution was cooled at the rate of approximately 2 F. per minute to a temperature of 0 F. The solid and liquid phases were separated at that temperature by filtration. The filtered solid was washed with 12 2 volumes of pentane and was then repulped with 2 volumes of pentane, and refiltered. The refiltered solid was then washed with 1 volume of pentane. By this means the decolorized wool grease was separated into a solid wool fat wax and a liquid wool fat oil. The wax, representing 29 weight percent of the deoolorized wool fat, had a meltin point of 52 C. and an iodine number of 30. The wool fat oil, representing 71 weight percent of the decolorized wool fat, had an iodine number of 60. The decolorized wool fat wax was a sterol product of high concentration and light color. The decolorized wool fat oil was a valuable product of light color which did not cloud on standing.

EXAMPLE II In this operation a dry, centrifugally recovered crude wool grease of relatively low free fatty acid content was continuously fractionated with butane in the same pilot plant equipment employed in Example I. In this operation, however, the crude wool grease was first neutralized by the addition of 1.7 weight percent of 10 percent aqueous sodium hydroxide solution, this representing a 50 percent excess over the theoretical requirement of alkali for neutralization of the free fatty acid. The resulting mixture was held at a temperature of 160 F., thoroughly stirred, and pumped into the first tower at the charge point, which in this operation was 9 feet from the top of the first tower. The conditions employed in this operation are set forth in the following table:

The results obtained in this operation are indicated in Table 6 below, in which are set forth analyses of the raw wool rease and the overhead and bottoms products.

Table 6' Charge Overhead Oil Yields, Wt. Percent Color, NPA

Color, Lovibond Free Fatty Acids, Percent (As Olei Free Fatty Acid Recovery, Percent.

Unsaponifiable Oil, Wt. Percen 45.8 49.0 22. 5 Unsaponifiable Oil Recovery, Per- Pour Point, F.

Ash, Wt. Percent. 015 0. 00 2. 84

Specific Gravity 0. 935 0.932

1 ASIM ring and ball.

The foregoing operation was conducted primarily as a treatment to neutralize and decolorize wool grease, and the foregoing data indicate that 13 this was successfully accomplished. The color (NPA) was reduced from 3- (single dilution) in the crude Wool grease to 3 in the overhead 14 ponents. The solid fraction was lighter in color than the oil. The free fatty acid content of the Wax was slightly higher than the oil, but its product. The neutralization also reduced the iodine value was only 40 compared with 62 in the acid content from 0.76 to 0.19 percent (as oleic). 5 oil. The deodorization had relatively small ef- The other physical and chemical properties of feet upon the properties of the materials other the overhead product differed only slightly from than the reduction of the odor. The color of the the crude grease. The inorganic material in the wax was increased from 35Y-4R to 50Y-5.6R, feed was removed in the bottoms product, in adwhile the oil Was reduced in color from '75Y-12R dition to the small amount of caustic added to l to 75Y l1R. The removal of traces of solvent neutralize the free fatty acids. Consequently the raised the specific gravity of each product 0.003. bottoms product had a high melting point and a The unsaponifiable oil content of the wax was low unsaponifiable oil content. less than that of the oil, indicating the removal The overhead product of Table 6 was subjected of the higher melting sterols from the liquid to fractional crystallization by chilling in prol product. pane to obtain a wool fat wax and a wool fat oil. Example III The oil and wax were separated by filtration, and In t peration crude wool grease, obtained the Wax W Washed Wlth fresh from the wool by solvent extraction with naphmove resldtlal 011 therefmm- 99116114510125 of tha, was treated to obtain a decolorized neutralthis operation for two operating periods are set m product During oneqlalf the operating forth below m Table period the crude wool grease was neutralized by Table 7 the addition of 6.5 weight percent of 20 percent aqueous sodium hydroxide solution, this repre- Operating Conditions: senting a percent excess over the theoretical gg figg gg gigt gg kg requirement. During the remainder of the op- Chilling Rate, F./Min 1 1 eration the crude wool grease was neutralized rut e tg n Tempcrature,F- with 2.7 weight percent of 50 percent aqueous Avgrag IIIIIIIIIIIII 1g 1 sodium hydroxide solution, this representing a 30 percent excess over the theoretical require- 1 1 53353$322251?3151;131:3113: 8. 2 5. 2 80 ment. The neutralized mixture was held at a fgg g g 2 26 4 3O temperature of 160 F., thoroughly stirred, and io /imut'fIII 2107 3125 pumped into the first tower of the pilot plant gzgffgg gff 2 2 referred to in previous examples. In this opera- Total Wash, v01. P'eYeeh'iIIIIIIIIIIIIIIIIII 264 194 tion the charge point was 9 feet from the top g f gg g ggggi Percent of the first tower. The conditions employed in 011, Wt. Percent 5a. 9 55.8 this operation are 'set forth in the following table: Wax, Wt. Percent 46.1 44. 2 Table 10 The wax and oil products of these two periods t p u were blended for product inspection. The blend- P 2 ed for product inspection. The blended products Feed 7 had the following analysis: Bottom 294 Table 8 Temperature grad1e nt, F./ft.:

Rectifying section 0.0 on Wax N Stripping section 0.43

Throughput, lb./hr./sq. ft. in 2-inch tower: T 1 Oil 240 83%35: fifittaee'21 areiiijjj iiiijjijj: 75m emit Butane 3340 Percent (AS 01m) 3 Butane velocity, ft./hr. in 2-inch tower 91.1 Pour P0int, 1 2g 13g Butane-to-oil ratio (by vol., F.) 22.4 f g gggg ggg gg g fl 62 40 Butane-swell ratio (by Wt.) 13.9 Residence time, min. 48.2 The W001 fat wax and the wool fat oil of Table Reflux ratio 0375 8 were stripped with steam to reduce the rela- He 1ght of q s 56011011, tively strong odor. In thi operation the oil or Helght 0f stl'lpplng Sectlon, wax was subjected to stripping with steam for d The results obtained in this operation are inone hour at a pressure of 4 mm. of mercury and dicated in Table 11 below, in which areset forth at a temperature of 225 F. Steam equivalent analyses of the raw wool grease and the overhead to 910 weight percent of the oil or wax was emand bottoms products. ployed. The deodorized wool fat wax and the 60 Table 11 deodorized wool fat oil had the following analyses:

Table 9 Charge Overhead gig;

011 Wax 4' 78. 7 21. 3 65 3e1e1- 1 v13 g.. t A 7aY7 R IIIIIIII 1 8385' 531mm1r 51611511312131: Y-1lR soy-51 1f F533 Fig? eie seZZ"v 3yP emeii3I i'sf 6. 2 Free fatty A id Percent (As Oleic) 0. 18 0, 26 Unsapon fiable O l, Wt. Percent 42. 3 49. 8 22. 2 Unsaponifiable 011, Wt Percent 53. 5 45.2 UnsaponlfiflblepllRecovery,Percent 92. 7 11.2 Iodine No. (Wijs). 62 40 I0d1nc No. (W1 s), 42 42 23 Cloud Point, 0 2 12 Sapomficat on 1:10-. 117 89 Pour p g Me tmg Po t, G. 40.4 78 Melting Point! 0 48.0 3E g Specific Gravity 951 1 Pour Point, 3F:-

Ash, Wt., Percen The fractional crystallization separated the Speclfic Gummy higher melting constituents from the liquid com- ASIM ring and ball.

The crude wool grease in this case was dark and had a relatively high fatty acid content. The overhead product was much lighter and had a substantially reduced fatty acid content. Inorganic material in the charge (0.08 percent) and the caustic used for neutralization were eliminated in the bottoms product which had an ash content of 2.39 percent. This inorganic material, in addition to the removal of the polymerized and oxidized material in the bottoms cut,

accounts for the high melting point of the bottoms product.

The foregoing examples illustrate various methods of operation of tower I in decolorizing wool fat. The examples also illustrate the further fractionation of a decolorized wool fat and the separation of a decolorized wool fat into wool fat wax and wool fat oil. The latter operations will be described in more detail by further reference to the drawings, which illustrate the combination of these steps with the decolorizing step in accordance with preferred modifications of the new process.

Referring to Fig. 1, the decolorized wool fat withdrawn from separator 29 through line 24 is admixed with cold solvent supplied from a cold solvent reservoir 38 through line 39, which is equipped with a pump 40. This cold solvent, similar in composition to the solvent employed in tower I0, replaces a portion of the hot solvent removed by evaporation at 29. The resulting mixture then flows through cooler 4| and the cooled mixture is then passed through valve 42 by which the pressure is released sufficiently to evaporate solvent to the extent necessary to produce the low temperature required for separating the decolorized wool fat into a wool fat wax and a wool fat oil. By this means the solution of decolorized wool fat is cooled to a temperature of approximately F. From the orifice of valve 42 the mixture is discharged into chilling tank 43, in which evaporation proceeds, with the formation of a slurry of wool fat wax in the solution of solvent and wool fat oil. The evaporated solvent passes overhead through line 44, compressor 45 and condenser 48 to cold solvent reservoir 38. The slurry is withdrawn from chiller 43 through line 41 for transfer to a continuous rotary filter 48. Preferably at least two chilling tanks, such as are shown at 43, are provided whereby one may be in use as a chiller while the other is discharging into filter 48. Advantageously this slurry from chilling tanks such as shown at 43 may be discharged into an intermediate filter feed tank, not shown, from which the slurry is continuously transferred to filter 48.

Cold solvent from reservoir 38 is transferred through lines 39 and 49 to a cold solvent tank 58, which is maintained at a lower temperature and lower pressure than reservoir 38. Cooling from the temperature at 38 is produced by indirect cooling at in line 49 and by partial evaporation of the cooled solvent by release of pressure at valve 52 in line 49. Cold solvent from tank 58 is transferred through line 53 by means of pump 54 to filter 48 for use in washing filter cake. A portion of this cold solvent is diverted through line 55 for use in reslurrying the washed filter cake. The slurry of filter cake is withdrawn through line 56, provided with pump 51. The filtrate solution is transferred from filter 48 through line 58 to filtrate solution tank 59. The filter is continuously blown back by gas introduced through line 68 from compressor 6 l, which 16 takes suction on tank 58 and tank 59 through lines 62 and B3.

The filtrate solution is withdrawn from tank 59 through line 64 which is provided with a pump 65 and heating means 66. Line 64 discharges into a high pressure fiash tower 61, in which the greater part of the solution is evaporated at the pressure of the outlet of compressor 45. The vaporized solvent passes overhead from flash tower 61 through line 68, which connects with line 44 on the upper side of compressor 45, whereby the vaporized solvent is condensed at 46 and returned to storage. The unvaporized liquid in flash tower 61 is withdrawn from the bottom thereof through line 69 and transferred to low pressure flash tower '10, in which most of the remainder of the solvent is evaporated. Vapors are withdrawn overhead through line H and transferred to line 68 by means of compressor 12. The wool fat oil remaining in drum I9 is transferred through line 13 to a vacuum stripper 14 in which the last trace of solvent is removed by steam introduced through line 15 and a vacuum imposed on line 16. The wool fat oil product is withdrawn through line 11.

The wool fat wax, withdrawn from filter 48 as a slurry through line 56, is transferred to a wax stripper 1B. The slurry is heated at 19 to a temperature above the melting point of the wax and sufficiently high to vaporize the solvent. vaporization is assisted by introducing steam into line 5'6 from line 19'. The wool fat wax product is withdrawn from stripper 18 through line 88 and the vapors pass overhead through line 8| to a jet condenser 82. The bottoms from condenser 82 are withdrawn through line 83 and the solvent vapors pass overhead through line 84, which connects with lin H and the entrance of compressor 72, in order to return the vapors to solvent storage at 38.

The bottoms product of fractionating tower H), which is withdrawn through line 31, may be subjected to further treatment simply for the recovery of solvent. For this purpose the liquid from line 31 is diverted through line 85 which is provided with a heater 86 and connects with a bottoms stripper 81. The pressure is reduced by means of valve 88 sufficiently low to evaporate in stripper 81, with the assistance of steam introduced at 89, substantially all the solvent present. The solvent vapors pass overhead through line 99 which connects with line 8i. Thus jet condenser 82 effects condensation of steam employed to assist vaporization in stripper l8 and stripper 81 and impose a vacuum on each of these vessels. The final bottoms product is withdrawn from stripper 8? through line 9!.

The foregoing treatment of the bottoms product of tower I8 is that which is employed ordinarily when no soaps are introduced into tower I9. When such soaps are present it may be desired to convert the soaps to fatty acids and then decolorize the fatty acid product thus obtained in a treatment similar to that of tower l8. For this purpose the bottoms from line 3'! are diverted through line 92. Acid, such as sulfuric acid, is introduced into line 92 from line 93. The resulting mixture passes through a suitable mixer 94 and the acidified mixture is introduced into settling tank 95. In tank 95 the lower aqueous phase is withdrawn through line 96 and the upper oily phase is withdrawn through line 91. The fatty acid product thus obtained may be withdrawn through line 98, but it is preferred to subject this product to decolorization treatment by'connecting line 91 with an intermediate point of the fatty acid decolorizing tower 99.

Tower 99 is generally similar in construction and operation to tower I9. Solvent at the necessary temperature is supplied through line I which connects with line It and is providedwith heating means NH. The operating conditions of tower 99 are selected to separate a small bottoms fraction containing the color bodies of'the original wool grease charge. This bottoms fraction conveniently may be treated to recover solventtherefrom by transferring it to line85 by means of lin H32. product is separated from the bulk of the solvent in reflux tank I63, from which the solvent vapors are transferred to line 32 through line iilfil'. The fatty acid product separated at Hisis transferred through line m by means of pump we to a high pressure flash drum ml, heat being supplied at I08. The fatty acid product is passed successive- 1y through high pressure flash tower Ii-il', low

pressure flash'tower Hi9, and stripper Iii whose method of operation is generally similar to that of vessels 37, Id and M. The solvent vapors in towers iil'land Hill are returned to storage at 38 by means of line i! i, which connectswith line 68, and by means of line i I2, which connects with line 54. The decolorized fatty acid product is withdrawn through line H3. Alternatively, the bottoms product from tower iii may be merely washed with solvent to remov color and the decolorized soaps may then be acidified.

Inevitably there occurs some loss of solvent from the system illustrated in Fig. 1, particularly in solution in the products. To replace such loss makeup solvent is introduced to hot solvent reservoir iI through line I2, as described above. There is, furthermore, a continuous flow of solvent from the circuit including reservoir II to the circuit including reservoir 33 in the form of the solvent mixed with the liquid withdrawn from reflux drums 29 and E63 and in the form of the solvent stripped from the bottoms from tower It. It may be that the flow of such solvent from the hot solvent circuit to the cold solvent circuit will be in excess of the amount required to maintain the necessary quantity of solvent in the cold solvent circuit. Line lid is provided to-return solvent from the cold circuit to the hotcircuit by connecting line 39 with line 32.

In the event it is desired to recover the decolorized wool fat as a final product, without separating it. into wool fat wax and wool fat oil, the reflux liquid passing through line 313 may be diverted through line i E- which connects directly with line 64. In that operation the whole de colorized wool fat product is recovered at "H.

Fig. Zillustrates the modification of the invention in which the wool grease is first'de colorized and the decoloriaed product then subjected to further fractionation in a second tower to obtain a relatively small overhead as a sterol concentrate. InFig. 2 certain parts of the apparatus of Fig. l. are duplicated, and such duplicate parts are indicated by the same reference numeral employed in Fig. 1, with the subscript a. t will be understood that the above description of the operation of the various parts of Fig. 1 applies also to such parts as are duplicated in Fig. 2. Referring to Fig. 2, the solvent phase passing overhead from tower i tic may be transferred directly to a second fractionating tower H5, by means of line II? which connects line ZBa With tower I i 8. Alternatively all the solvent phase from towerits may be treated to re.

The decolorized fatty acid- 18 move solvent therefrom in drum 2921' as described in connection. with Fig. 1, and the reflux liquid separated-in. 29a may be passed tov tower IIB by diverting the liquid passing through line 34a to .tower IIB through-line lla, by means of pump Fractionating'tower I I6 is generally similar in construction and operation totower Iiia and is adapted to impose on thezdecolorizedwoolfat operating conditions which fractionate thede colorized wool fat intoa relatively small overhead fraction constituting approximately 5-15 percent of the decolorizedwoolfat andabottoms fraction comprising the remainder of thedecolorized wool fat.. Operating conditions for tower i I 6 are generally similar to-those employed in tower 19a except that, in view of the smaller overhead fraction, somewhat higher operating. temperatures are-employed. The operating conditions for fractionating wool fat in this manner are exemplified by -Table2 above.

Thesolvent for tower H6 is supplied by line I29 which is provided with a pump I2! and heating means I22 and connects line I4a-with a low-point of tower H6. The ratio of solvent charged through line I20 .110 wool. fat charged through lines II? or- H8 is of the same order ofliquid phase material is withdrawn from drum. I24 throughline I25 which connects with a high. Line I25 is provided.

pressure flash. tower I28.

with pump I29 and heating means E30. The

overhead product ispassed successively through highpressure flashtower I28,.-low pressure flash tower I3I and stripping tower. I32, which .op-

erate in the manner described in connection,

with towers 61, i0 and M. The small overhead product, representing a sterolconcentrate ofthe wool fat, is withdrawnzas aproduct through line I33- A portion of the liquid collected in drum I24 is passedthrough line I34 and pump. i35 tov the top of tower IIB as reflux.

The product removed from the processv through line I33 represents. a desirable derivative of wool fat. because of its high concentration of sterols and as such-represents a valuable product. However, it may be desirable to subject this. product to separation into oil and wax. components by means of the operation described in connection with chiller 43 andfllter 48 of Fig. 1. It may be desirable, therefore, to pass the liquid withdrawn from drum I24 to the operation of Fig. l which is applied to the liquid flowing through line. 34 of that figure.

The remainder of the decolorized Wool fat is separated as the rafiinate or bottoms fraction in tower I I 6 and withdrawn. therefrom-through line I 35. It may be desirable to divert a portion of this liquid through line It: by means of pump 538 for passage to a higher point in tower Illa as reflux liquid.

The remainder of the lower phase material withdrawn from tower llt through line I35 is subjected to further treatment in accordance with the treatment of material withdrawn from drum 29 of Fig. 1 through line 34 of that figure. This may involve simply treatment of this product to separate solvent therefrom, or it may involve the separation of this product into wool fat oil and wool fat wax in accordance with the procedures described in connection with chiller 43 and filter 48 of Fig. 1.

The operation illustrated by Fig. 2 thus involves the separation of the wool fat into a small bottoms fraction containing the color bodies and, possibly, the soaps, separated in tower Hla, a small overhead fraction, representing a sterol concentrate, from tower I I6, and a relatively large bottoms fraction, representing a decolorized wool fat, from tower H6. These fractions may be further treated by the means illustrated in Fig. 1 to recover a fatty acid fraction and wool fat oil and wool fat wax fractions.

We claim:

1. A process for refining wool fat which comprises contacting said wool fat with an alkaline neutralizing agent to convert free fatty acids to soaps, contacting the resulting mixture of soaps and neutralized wool fat with a relatively lowtion of the wool fat and said soaps, and recover ing a refined wool fat from the extract.

2. A process for refining wool fat which comprises contacting said wool fat with an alkaline neutralizing agent to convert free fatty acids to soaps, flowing the resulting mixture in countercurrent contact with an oppositely flowing stream of a relatively low-boiling liquefied solvent whose critical temperature is lower than 325 F., maintaining the temperature of said counter-current contact above the temperature of maximum solubility of the neutralized wool fat in the solvent and not lower than 100 F. below the critical temperature of the solvent and under pressure eifective to maintain liquid phase conditions, to dissolve a major proportion of the neutralized wool fat in the solvent and reject a minor proportion of neutralized wool fat and the soaps, and recovering a refined wool fat from the extract.

3. The method of claim 2 wherein the extract solution is further treated by counter-current contact with extract previously separated from extract solution produced in a similar operation.

4. The method of claim 2 wherein a portion of the solvent contained in the extract solution is evaporated to chill the remaining extract solution to a relatively low temperature to separate a portion of the extract as a solid phase, the phases are separated, a wool fat wax is separated from the solid phase, and a wool fat oil is separated from the liquid phase.

5. A process for refining wool fat which comprises contacting said wool fat with an alkaline neutralizing agent to convert free fatty acids to soaps, introducing the resulting mixture of neutralized wool fat and soaps into a vertically elongated fractionating zone, subjecting the mixture of wool fat and soaps in said zone to countercurrent contact with a stream of solvent consisting essentially of a liquefied normally gaseous hydrocarbon containing at least 3 carbon atoms per molecule and introduced as a stream into said zone at a low point thereof, maintaining the fractionating zone at a temperature effective to dissolve in said solvent stream a major proportion of the neutralized wool fat while rejecting a minor proportion of the wool fat and the soaps, withdrawing the rejected wool fat and soaps from a low point in the fractionating zone, flowing the extract solution upwardly in said zone past the point of introduction of said mixture of Wool fat and soaps, flowing downwardly in that portion of said zone above said point of introduction of the mixture of wool fat and soaps a separate lower liquid phase consisting essentially of wool fat previously separated from a similar extract solution, intimately contacting the separate liquid phases in the fractionating zone above the point of introduction of the mixture of wool fat and soaps, withdrawing extract solution from said fractionating zone at a point near the top thereof, and recovering refined wool fat from the withdrawn extract solution.

6. The method of claim 5 wherein the extract solution is withdrawn from said iractionating zone, a portion of the solvent contained therein is permitted to evaporate to cool the remainder of the solution to a low temperature to precipitate a portion of the extract as a separate solids phase, the phases are separated, a wool fat wax is recovered from the solids phase, and a wool fat oil is recovered from the liquid phase.

'7. A continuous process for refining wool fat by countercurrent fractionation with a solvent having a critical temperature of less than about 450 R, which method includes the steps of forming a liquid mixture of said wool fat and an alkali adapted to neutralize said wool fat; continuously charging said mixture and said solvent into a vertically extended fractionation zone having an extract phase outlet near its upper end, a solvent inlet and raflinate phase outlet near its lowerend, and a charge mixture inlet intermediate said ends; intimately contacting said mixture and said solvent within said fractionation zone at temperatures within the range near the critical temperature in which solubility decreases as temperature increases, to precipitate a rafiinate phase containing substantially all soaps formed by contacting said alkali with said wool fat and to form an extract phase containmg wool fat substantially free of said soaps and color bodies; separately withdrawing said extract and raifinate phases from said extract and raffinate phase outlets respectively; and recovering a refined wool fat product from said extract phase.

8. A process of treating crude wool fat containing a substantial amount of sterols and sterol esters obtained from wool scouring waters to produce a fraction rich in sterols and sterol esters, which comprises subjecting the crude wool fat to a two-stage liquid phase solvent treatment in the presence of a liquefied normally gaseous hydrocarbon solvent, maintaining conditions of temperature within a range between about 20 F. above the critical temperature of the solvent and a temperature of about F. below said critical temperature and under liquefying pressure whereby in the first stage color bodies are separated and the wool fat is substantially decolorized, maintaining conditions of liquefying pressure and substantially higher temperature in the second stage whereby a fraction relatively rich in the sterols and sterol esters is separated from the decolorized product and recovering said frac 21 tion rich in sterols and sterol esters from said second stage.

9. A process for the recovery of sterols and sterol esters contained in crude fatty material obtained from wool scouring waters, which comprises subjecting the said fatty material to a decolorizing operation in the presence of a liquefied normally gaseous hydrocarbon solvent at temperatures ranging from about 100 F. below the critical temperature up to the critical temperature and at liquefying pressures, such that the color bodies separate as a liquid phase, separating said liquid phase from the decolorized fatty material, subjecting said decolorized fatty material to a fractionating operation under conditions of liquefying pressure and substantially higher temperature such that a fraction relatively rich in said sterols and sterol esters separates as a liquid phase from a heavier phase containing the major portion of the fatty material, and separating the phases.

10. A process for the recovery of sterols and sterol esters contained in the wool fatty material obtained from wool scouring waters which comprises subjecting the said fatty material to a decolorizing operation in the presence of liquefied propane solvent at temperatures of from about 110 F. to about 174 F. and under liquefying pressure so that the color bodies separate as a liquid phase, separating said liquid phase from the decolorized fatty material containing the sterols and sterol esters, subjecting said decolorized fatty material to a fractionating operation in the presence of additional said solvent, increasing the temperature in said operation to within a range of from about 183 F. to 217 F. and under liquefying pressure so that two phases are formed, one of said phases being relatively rich in fatty material, and separating said phase rich in sterols and sterol esters.

11. A process for treating crude wool fat containing a substantial amount of sterols and sterol esters obtained from wool scouring waters to produce a fraction rich in sterols and sterol esters, which comprises subjecting the crude wool fat to a two-stage liquid phase solvent treatment in the presence of a liquefied normally gaseous hydrocarbon solvent, maintaining in the first stage conditions of temperature within a range betweenabout 20 F. above the critical temperature of the solvent and a temperature of about 100 F. below said critical temperature and under liquefying pressure whereby color bodies are separated and the wool fat is substantially decolorized, evaporating said liquefied normally gaseous hydrocarbon solvent from said decolorized wool fat to cool said wool fat to a temperature of approximately 0 F. in the sec-- 0nd stage whereby a fraction relatively rich in the sterols and sterol esters is precipitated from the decolorized product, and recovering said precipitated fraction rich in sterols and sterol esters from said second stage.

12. A process according to claim 1 in which after said wool fat is contacted with said alkali neutralizing agent, a part of the soap is settled from the resulting mixture of soap and neutralized wool fat, and the remaining mixture of soap and wool fat is then contacted with said liquefied solvent.

HERBERT J. PASSING. JAMES M. MIEYERS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 539,388 Maertens May 14, 1895 540,256 Jaife et a1 June 4, 1895 548,942 Wingfield Oct. 29, 1895 1,383,585 Wilson July 5, 1921 1,974,542 Parkhurst et a1. Sept. 25, 1934 2,118,454 Schaafsma May 24, 1938 2,285,795 Batchelder June 9, 1942 2,288,441 Ewing June 20, 1942 2,329,889 Ewing Sept. 21, 1943 2,417,329 Snyder Mar. 11, 1947 2,528,482 Young et al. Oct. 31, 1950 

1. A PROCESS FOR REFINING WOOL FAT WHICH COMPRISES CONTACTING SAID WOOL FAT WITH AN ALKALINE NEUTRALIZING AGENT TO CONVERT FREE FATTY ACIDS TO SOAPS, CONTACTING THE RESULTING MIXTURE OF SOAPS AND NEUTRALIZED WOOL FAT WITH A RELATIVELY LOWBOILING LIQUEFIED SOLVENT WHOSE CRITICAL TEMPERATURE IS NOT SUBSTANTIALLY HIGHER THAN 450* F. AT A TEMPERATURE ABOVE THE TEMPERATURE OF MAXIMUM SOLUBILITY OF THE WOOL FAT IN THE SOLVENT AND NOT LOWER THAN 100* F. BELOW THE CRITICAL TEMPERATURE OF THE SOLVENT AND UNDER PRESSURE EFFECTIVE TO MAINTAIN LIQUID PHASE CONDITIONS, TO EXTRACT A PORTION OF THE WOOL FAT AND REJECT ANOTHER PORTION OF THE WOOL FAT AND SAID SOAPS, AND RECOVERING A REFINED WOOL FAT FROM THE EXTRACT. 